Specific binding assays, for example immunoassays, which take advantage of natural binding reactions, have found wide-spread use as analytical techniques in clinical chemistry. Because of the specificity of the reactions, they are particularly advantageous in quantifying biological analytes that are present in very low concentration in biological fluids. Such analytes include, for example, antigens, antibodies, therapeutic drugs, narcotics, enzymes, hormones, proteins, etc.
Many dyes or colorants (hereinafter "dyes") are used in commercial immunoassay coating procedures to aid monitoring of the dispensing of a reagent or spectrophotometric monitoring of the dispensing of reagent. Many of the dyes are commercially available. Basically, the dye allows for visual detection. This can be particularly useful in monitoring the dispensing of solutions into vessels, e.g., microwells during manufacturing processes for coating biological materials onto the surface of the microwells. The coated vessels are subsequently used as solid phase in immunoassays. It is desirable that the dyes that are used do not interfere with the biological nature of proteins, which are coated onto the solid phase support. However, some proteins can interact with dyes and, as a result, this interaction reduces assay performance. For example, this has been a recognized problem in the manufacturing of microwells for assays for detecting antibodies to hepatitis C virus (HCV).
Therefore, one object of the present invention is to provide a dye that can be used in a solid phase coating comprising HCV antigens and to aid the monitoring of microwell fill volume and yet, does not have a detrimental effect on proteins, specifically HCV antigens, present in an anti-HCV assay. Another object of the present invention is to provide a dye that will actually improve assay performance.